Speedometer-controlled switch



E. A. M GRATH SPEEDOMETER CONTROLLED SWITCH Filed 001.. 21

Patented Oct. 12, 1926.

UNITED STATES PATENT OFFICE.

EDWARD A. MCGRATH, OF MEDFORD, MASSACHUSETTS, ASSIGNOR OF ONE-HALF TCWALTER E. BURKE, 0F QUINCY, MASSACHUSETTS.

SPEEDOMETER-CONTROLLED SWITCH.

Application filed October 21, 1924.

This invention relates to an improved speed controller, particularlyadapted for use in conjunction with the speedometer installed inautomobiles, which operates automatically to give a signal when anillegal rate of speed has been attained by the car.

It is a well known fact that rivers of automobiles do not watch thespeedometer when driving and that, due to the difiiculty ofinstinctively gaging the rate of speed of a car, the legal speed isfrequently exceeded unconsciously. It is an object of this invention torender constant reference to the speedometer reading wholly unnecessaryby providing an audible signal to warn the driver whenever the rate ofspeed equals or exceeds the legal rate. The invention further providesfor a visual signal, that is maintained constantly operative While thecar is travelling at or above the illegal speed, and is so placed thatit is readily seen by drivers of approaching cars or oflicers of thelaw.

To the accomplishment of this object and such others as ma hereinafterappear, as will readily be un erstood by those skilled in the art, theinvention comprises the features and combination of arts hereinafterdescribed and then particu arly pointed out in the appended claims. I

The various features of the invention will best be understood from adescription of the preferred embodiments thereof illustrated in theaccompanying drawing.

In the embodiment of the invention illustrated in the drawing,

Figure 1 is a view, in front elevation, of one form of the inventionapplied to a speedometer of the Stewart-Warner type, the front casingbeing removed;

Figs. 2 and 3 are views, in plan, showing the inoperative and operativepositions of the trigger which closes the electric circuit shown in Fig.1;

Fig. 4 is a view, in front elevation, of

another form of the invention but also employing a circuit making andbreaking trigger, the circuit being open in this view; and

Fig. 5 is a view, in plan, of the form of the invention shown in Fig. 4,the circuit being closed in this view.

In the embodiment of the invention illustrated in Figs. 1, 2 and 3 ofthe drawing, 10 represents a speedometer of the Stewart- Warn'er typewithin the casing 12 of which Serial N 0. 744,946.

is mounted the drum dial 14, having the usual lug 15 for engaging a stop16 under the influence of the return spring 18, thus maintaining 0 onthe dial registered with the sight opening in the face (not illustrated)when the car is at rest.

Mounted on the casing 12, conveniently at the left side of the casing,is a shell 20 which supports the device for energizing an electriccircuit 22 (Fig. 1) and operating a signal such as the buzzer 23 or lamp24, or both, whenever a rate of speed is attained that equals or exceedsthe legal limit. The circuit making and breaking is determined by anoscillatory trigger 26 the movement of which is controlled by theengagement therewith of a trip lug 28 on the drum dial 14. l

The trigger is secured to a rock-shaft 30 having its upper end journaledin a bearing 32 and its lower end stepped in a wall of the shell 20. Thespeedometer casing is slotted at 34 permitting the inner end of thetrigger to project therethrough. This end is forked, providing two triparms 36 and 38 which lie alternately on center and in the path of thetrip lug 28 upon travel of the lug in a direction to respectivelyaccelerate or decelerate'the speed of the car in which the speedometeris installed. The outer end 40 of the trigger constitutes means forclosing the circuit by engaging an electric contact 42 in one angularposition of the trigger.

The trigger 26 is maintained in one or the other of its angularpositions, illustrated by Figs. 2 and 3, by a contractile spring 44,continually under tension but weaker than the drum dial return spring18. One end of this spring 44 is adjustably connected at 45 to a wall ofthe shell 20 and its other end is connected to one side of a loop 46,surrounding the rock-shaft 30, the other side of which is pivotallymounted on a pin 48 depending from the trigger inside the rockshaft. Itwill be observed that the distance from the pin 48 to the rock-shaft isconsiderably less than from the in 48 to the pivotal springconnection45. onsequently the arc of travel of the pin 48, as the trigger swingsfrom one extreme position to the other, causes the spring 44 to beextended as the trigger crosses center and then immediately contract,snapping the trigger quickly into its new angular position.

The trip lug 28 1S located at such a point on the periphery of the drumdial that as the speed of the car increases it will meet the trigger arm36 and turn the trigger ust past center when the illegal speed markingon the dial registers within the sight opening. As illustrated, thesetting is tor indieating an illegal speed of thirty miles per hour.Fig. 2 illustrates the position of the parts when the trip lug, movingin the direction of the arrow, is nearing the trigger arm 36. therebeing no current flowing in the circuit at this time. In Fig. 3 thetrieger 26 has been pushed across the center by the moving trip lug 28and the spring at has functioned to turn and hold the trigger in theposition in which its end 10 engages the contact 42 thus closing theelectric circuit and energizing the buzzer 23 to sound a warning to thedriver.

It the automobilelaws require a visible notice to otiicers ot' the law,and other drivers on the road that the legal speed is being exceededthen the lamp 2% is connected in the circuit and is mounted on someprominent part of the car, preferably on the mud guard above theleftlfront whee-l where the driver also cannot fail to see it.

It will be observed from the position of the trip lug 28 in Fig. 3 thatcurrent continues to flow through the circuit 22 on. con tinuedacceleration of the speed above the legal limit. the warning signalsthus being continuously operated until the trigger :26 is turned back toits position shown in Fig. 2. On hearing. or seeing, the warning signalthe prudent driver will throttle down his engine thus causing the drumdial 1-l to rotate in a direction 01 posits to that oflthe arrow on Fig.2 and at the time the speedometer registers 30 the trip lug will have t.ged the trigger arm 88 and moved the or to center. thus breaking thecircuit 22. v below 30 miles per hour the spring ts functions again tosnap the trigger to the position of Fig. 2 and hold it there. Theforward wall 35 ot the slot acts as a stop for the trigger when. in thisposition.

Attention called to the design of the trip lug 28. This lug should be soproportioned ive to the distance between the trip arms 36 and that on anacceleration oi" the speed of the car its forward wall 27 (Fig. 9) willhave engaged and brought the trigger across enter when the speedometerregisters "30 so that the spring at may inm'iediately function to closethe electric circuit, and on a deceleration ol the speed of the ear itsrear wall 29 (Fig. 3) will have engaged and moved the trigger arm 38sufficiently to break the circuit. when the speedometer registers 30".By making the width of the trip lug substantially onehalf the distancebetween the trigger arms this end is attained and extreme accuracy ofoperation is insured.

In the form of the invent-ion illustrated in Figs. 4 and 5 the partshaving the same reterence characters are similar to those of thepreferred construction. In this form a torsion spring 50 is connected tothe rockshaft 30 and to the speedometer casing in such manner that thetrigger 26 continually tends to seat against the slot wall 35. When thetrigger 26 is turned to the position of Fig. 5 by the advancing trip lug28 then an upstanding piece of light spring .ietal 52 at its outer endis snapped under the lower edge of the vertically arranged contact 4.2.The upper end of the spring piece 52 may be curved or beveled so as toact as a latch to keep the circuit closed against the tendency of thespring 50 to return the trigger to its initial position. When the triplug retreats during a deceleration ot the speed its pressure on thetrigger arm 38 unlatches the piece thus breaking the circuit. and thespring 50 functions to re turn the trigger to a position with its arm 36in the path of the trip lug.

In accordance with my invention a circuit maker and breaker is providedthat ma be operated perfectly by the delicate spec omeler controlmechanisn'i, and also is so light and easily operated that no dragwhatever is placed on the drum dial, permitting the dial to registerwith the same accuracy as when the speed indicating controller is notpresent.

That an illegal-speed signal attachment shall operate without materiallyhindering the movements ot' the drunrdial is imperative in the type ofspeedometer now in general use. as the drum-dial must be actuated withsuch delicacy that the slightest drag will interfere fatally with thathigh standard of accuracy which is demanded in this class oi. devices.In my device, I avoid all appreciable drag on the dial not only bykeeping the switch oil the dial-drum, but also by so constructing theparts that the switch will be thrown by the dial by an exceedingly lighttouch; and, furthermore, this light engagement of the dial with theswitch is but momentary. i. e., just long enough to carry the switchover center through an arc of a small fraction of an inch in length.

In both illustrated forms of the invention the trigger constitutes anelectric switch, the position of which is automatically controlled by apredetr-n'znined rate of speed of the car as registered by thespeedometer, whether the trigger be given its quick movement b r aspring or otherwise. It will be understood, however, by those skilled inthe art that my automatic speed controller may be operated with equalfacility by any moving actuator installed on the car which changes itsposition in accordance with variations in the rate of speed, above andbelow apredetermined limit, as does the drum dial of a speedometer.

While it is preferred to employ the specific construction andarrangement of parts shown and described it will be understood that thisconstruction is not essential except so far as specified in the claims,and may be changed or modified without departing from the broaderfeatures of the invention.

lVhat is claimed as new, is z 1. Speed indicating mechanism forautomobiles having, in combination, a speedometer having a dial membermovable in one direction as the rate of speed increases and in theopposite direction as it decreases, a trigger at a predetermined pointin the path of said member and movable to two different positions tomake andbreak a circuit, a device associated with the movable member inposition to momentarily engage said trigger to shift it to one positionor the other, and means independent of said movable member formaintaining said trigger in the position it assumes after engagement bysaid movable member.

i 2. Speed indicating mechanism for automobiles having, in combination,a speedometer having a dial member movable in one direction as the rateof speed increases and in the opposite direction as it decreases, atrigger independent of said movable member and located at apredetermined point in the path of said member and movable to twodifferent positions to make and break a circuit, a device associatedwith the movable member in position to momentarily engage said triggerto shift it to one position or the other, and means for maintaining saidtrigger in the position it assumes after engage ment by said movablemember and after said member has travelled beyond the trigger in onedirection or the other.

3. Speed indicating mechanism for automobiles having, in combination, anoscillating dial member movable in a fixed path and controlled by thespeed of the car, a pivoted trigger extending in the path of said memberto be momentarily engaged by the member during its travel whereby tomove the trigger in a direction to close a circuit.

4. In combination with a speedometer embodying a speed-indicatingdrum-dial and vehicle-driven means for oscillating it axially toindicate changes in the speed of the vehicle, of an illegal-speedindicating means therefor embodying a tappet or lug on the drum-di a1, aquick-acting trigger pivotally mounted independently of the drum- .dialin position to be thrown in either direction by momentary contact withsaid tappet or lug at a predetermined position of the drum-dial, and aswitch associated with said trigger which will be closed in one positionof the trigger and open in its other position.

5. Speed indicating mechanism for automobiles having, in combination, apivotally mounted switch, a member movable in opposite directions pastsaid switch as the speed of the car is accelerated or deceleratedconstructed and arranged to have but a momentary contact with the switchand cause it to be thrown to one side or the other to make or to break acircuit whenever the po sition of said member indicates a predeterminedrate of speed, and means to hold the switch in the position to which itis thrown until the member again indicates the predetermined rate ofspeed regardless of variations from said rate during the interveninginterval.

6. The combination with a speedometer having a slot through its casing,of a pivotally mounted quick-acting trigger projecting inward throughsaid slot, a member on the trigger for closing a circuit when thetrigger is turned in one direction on its pivot, and a trip lug on thedrum dial proper positioned to momentarily engage the trigger and causeit to be turned in said direction when the speedometer registers a predetermined rate of speed.

7. The combination with a speedometer having a slot through its casing,of a pivotally mounted trigger projecting therethrough having a forkedend within the casing, a trip lug on the drum dial proper positioned tomomentarily engage one leg of the fork, when a predetermined rate ofspeed is reached while the speed is being accelerated, to swing thetrigger to one side and close a circuit and to engage the other leg ofthe fork, when said rate of speed is reached while the speed is beingdecelerated, to swing the trigger to the other side, and means forquickly actuating said -trigger away from said lug into its finalposition at one side or the other and maintaining such position untilagain engaged by said trip lug.

8. The combination with a speedometer having a slot through its casing,of a pivotally mounted trigger projecting therethrough having a forkedend within the casing, a trip lug on the drum dial pro er positioned tomomentarily engage one eg of the fork, when a predetermined rate ofspeed is reached while the speed is being accelerated, to swing thetrigger to one side and close a circuit and to engage the other leg ofthe fork, when said rate of speed is reached while the speed is beingdecelerated, to swing the trigger to the other side, said trip lughaving a width of substantially one-half the distance between the twolegs of said fork, and means for quickly actuating said trigger awayfrom Said lug into its final position at one side or the other andmaintaining such position until again engaged by said trip lug.

9. The combination with a pivotally mounted switch, of a speedometerprovided with a trip lug on its drum dial proper adapted to engage saidswitch momentarily only, when the speedometer registers a predeterminedrate of speed, and move it across center, and a spring for snapping theswitch into position for closing a circuit.

10. The combination with apivotally mounted switch and a-spring actingupon said switch in a manner to hold it in an an gular position ateither side of dead center, in one of which positions a circuit isclosed and in the other of which open, of a speedometer provided with atrip lug on its drum dial proper adapted to momentarily engage theswitch while in one angular position, upon registration of apredetermined ate of speed through either acceleration o1 deceleration,and swing it across center whereupon said spring operates to snap theswitch away from said lug into its other angular position.

11. Qpeed indicating mechanism for antomobiles having, in combination,an electric circuit including a signal device, a member movable in onedirection as the rate of speed increases and in the opposite directionit decreases, and a device independent of said member in said circuitarranged in the path of said member adapted to be en gaged momentarilyand-moved by said mem-- her in one direction or the other according asthe rate of speed is increasing or decreasing to respectively close andopen the circuit, the movement of said device in either directioncarrying it out of said path and out of engagementwith said member,whereby continued movement of said member in its direction of travel isunhampered.

12. Speed indicating mechanism for antomobiles having, in combination,an electric circuit including a signal device, a member movable todifferent positions as the speed of the car increases and decreases, adevice independent of the movable member in said circuit arranged in thepath of said member and at a .point in said path indicating apredetermined rate of speed and momentarily cooperating with said movingmember when passing said point to close the circuit and energize saidsignal, amd yielding means operating through said device to maintain thecircuit closed until said member again passes said point in its courseof travel.

EDWARD A. MOGRATH.

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1,602,799, grantedOctober 12, 1926, upon the application of Edward A. McGrath, of Medford,Massachusetts, for an improvement in Speedometer-Oontrolled Switches,errors appear in the printed specification requiring correction asfollows: Page 4;, lines 25 and 26, claim 11, strike out the words andcomma an electric circuit including a signal device,; line 30, strikeout the Words in said circuit, and line 35, for the article the read a,same page, lines 412 and 43, claim 12, strike out the words and comma anelectric circuit including a signal device,; lines 46 and 417, strikeout the Words in said circuit, and line 51, for the article the read a;same claim, lines 51 and 52, strike out the Words and energize saidsignal; and that the said Letters Patent should be read with thesecorrections therein that the same may conform to the record of the casein the Patent O'flice.

Signed and sealed this 16th day of November, A. D. 1926.

[SEAL] M. J. MOORE,

Acting Co'lmm'ssz'mter of Patents.

-Certificate of Correction.

It is hereby certified that in Letters Patent No. 1,602,799, grantedOctober 12, 1926, upon the application of Edward A. McGrath, of Medford,Massachusetts, for an improvement in Speedometer-Controlled Switches,errors appear in the printed specification requiring correction asfollows: Page 4, lines 25 and 26, claim 11, strike out the words andcomma an electric circuit including a signal device,; line 30, strikeout the Words in said circuit, and line 35, for the article the read a;same page, lines 42- and 43, claim 12, strike out the Words and comma anelectric circuit including a signal device,; lines 4:6 and 4L7, strikeout the Words in said circuit, and line 51, for the article the read a;same claim, lines 51 and 52, strike out the Words and energize saidsignal; and that the said Letters Patent should be read With thesecorrections therein that the same may conform to the record of the casein the Patent Oflice.

Signed and sealed this 16th day of November, A. D. 1926.

[SEAL] M. J. MOORE,

- Acting Uommissz'ower of Patents.

